In recent years, various wearable devices have been released. The wearable device is a type of a computer used by a user with the wearable device on. The wearable device is effective as a device which notifies information to the user. For example, as to an eyeglass-type wearable device, when incoming call is detected, an icon etc. is overlappingly displayed on actual scenery which is visually recognized through the glass part to notify the incoming call. On the other hand, the wearable device is not suitable for complicated operations. Thereby, in many cases, the wearable device is used in combination with portable information terminals such as smart phones, cell phones, tablet PCs which can easily handle the complicated operation.
It is general that a security lock (hereinafter referred to as “lock”) is set on the portable information terminal to authenticate a user before operation. Similar to this, when the wearable device is used, the user is authenticated. For example, the eyeglass-type wearable device performs biometrics authentication, through which, the user is authenticated by means of his eyes. For example, in an eyeglass-type user terminal device disclosed in Patent Literature 1, authentication is performed based on image information of the user's eye. Also, in an eyeglass-type interface device disclosed in Patent Literature 2, the image of the retina of an eyeball of a user is photographed and authentication is performed in accordance with the result. In an eyeglass-type image display device disclosed in Patent Literature 3, the image of the eye of the user is photographed and iris authentication for the user is performed.